Splash-proof leak-proof syringe-type cryosurgical instrument

ABSTRACT

A generally tubular splash-proof leak-proof syringe-type cryosurgical instrument formed of merging chambers is described. The generally tubular instrument is shaped in the silhouette of a finger tip at the end of a lower chamber. The lower chamber is surrounded by a thermal insulating layer and supports a thermal conducting probe that communicates between the interior of the instrument and the exterior thereof. A generally funnel-shaped member having internal ribs is mounted in the upper end of the instrument. The internal ribs support the space the base of an actuator-insertion cap from the funnel-shaped member so that an escape-port passageway is provided. The actuator-insertion cap has an outwardly extending transfer tube somewhat longer than the longitudinal length of the funnel-shaped member, and is attachable to a canister of refrigerant fluid. The actuatorinsertion cap assists the passage of the fluid through the funnel-shaped member into the interior of the housing. That is, the actuator-insertion cap is adapted to cause the canister to emit a cryogenic liquid refrigerant which flows through the transfer tube portion of the cap iunto the interior of the housing when the tube is inserted into the instrument along the longitudinal axis of the funnel-shaped member. The interior air that is displaced by the liquid refrigerant, as well as the evaporating gas of the liquid refrigerant entering the instrument escape via the escape-port passageway.

[ 1 Mar. 5, 1974 SPLASH-PROOF LEAK-PROOF type cryosurgical instrument formed of merging cham- SYRlNGE-TYPE CRYOSURGICAL hers is described. The generally tubular instrument is INSTRUMENT shaped in the silhouette of a finger tip at the end of a I lower chamber. The lower chamber is surrounded by a Inventors A a g thermal insulating layer and supports a thermal conb 8 on prmgb ducting probe that communicates between the interior 0 0 of the instrument and the exterior thereof. A generally Assignee: The Du-Al Company, Laur l, Md. funnel-shaped member having internal ribs is mounted in the upper end of the instrument. The internal ribs Filed. Apr. 29, 9 support the SPflC the'base of an actuator-insertion Appl. No.: 138,686 cap from the funnel-shaped member so that an cscape-port passageway is provided. The actuatorinsertion cap has an outwardly extending transfer tube somewhat longer than the longitudinal length of the 62/115 55 funnel-shaped member, and is attachable to a canister 0 earc of refrigerant fluid. The actuator-insertion cap assists the passage of the fluid through the funnel-shaped Refelenlies Cited I member into the interior of the housing. That is, the

UNITED STATES PATENTS actuator-insertion cap is adapted to cause the canister United States Patent Allen, Jr. et al.

to emit a cryogenic liquid refrigerant which flows through the transfer tube portion of the cap iunto the interior of the housing when the tube is inserted into 7 the instrument along thelongitudinal axis of the funnel-shaped member. The interior air that is displaced by the liquid refrigerant, as well as the evaporating gas of the liquid refrigerant entering the instrument escape via the escape-port passageway.

12 Claims, 10 Drawing Figures 555 ll r. 445 .k e UWW OO m m 0 666 33 .I z w B r u 88 y n 22 d S l 3 n f n n n a 0 m in m m m m mnnm g D. m t m m a a u U R 6 m"..m l ununun f n m m T 0 m m Mm u C m "a mt" A P n ""0." .n R. r .l h S G h e nl n T s d y n S a u .wc m a m v RWBKDS h A S m r 252670 1 456567 6 u 999999 n b HHHHHH m u 767590 m t I dun y n H 780444 m 877649 y e ,1 ,5 n D 54632 r e 9 4441 mo 7 2. 1 7 1 W 5 233233 PA [A PATENTED 51974 SHEET 1 BF 2 FIG. 1

INVENTORS ROBERT E. ALLEN, JR. RICHARD A. MOREL ATTORNEYS PATENTEUNAR sum SHEUZUFZ FIG] SPLASH-PROOF LEAK-PROOF SYRINGE-TYPE CRYOSURGICAL INSTRUMENT BACKGROUND OF THE INVENTION vention falls within the latter general class of cryosurgical instruments. More specifically, this invention is an improvement to the invention described in U.S. Pat. No. 3,536,076 issued to Robert E. Allen, Jr., for a Leak-Proof Syringe-Type Cryosurgical, Instrument, reference being made thereto for a more complete description of prior art cryosurgical instruments and their disadvantages. Reference is also made to US. Pat. No. 3,536,076 for a' general description of the use of cryosurgical instruments in the performing of various types of medical cryosurgical procedures and operations.

While the invention described in US. Pat. No. 3,536,076 overcomes many of the disadvantages of the prior art cryosurgical instruments generally described .therein, particularly with respect to the feel of the instrument and the prevention of the leakage of the liquid refrigerant, it has been found that certain improvements that better overcome those and other disadvantages of prior art devices can be made to that invention. For example, it has been found that while the funnelshaped structure and overall silhouette of the instrument described in US. Pat. No. 3,536,076 perform the desired functions, certain improvements can be made thereto which perform these functions in a still better manner, such as increasing the fluid holding capacity of the instrument and improving the ability of the instru-- ment not to leak when inverted, for examples. In addition, while the location of the probe in the US. Pat. No. 3,536,076 device is generally satisfactory, it has been found that by slightly changing the location of the probe, the instrument becomes somewhat easier to use. Further, it has been found that by using a particular insertion cap, ease of introducing a cryogenic fluid into the instrument withoutsplashand spillage is improved,

Therefore, it is an object of this inventionto provide a new and improved cryosurgical instrument.

It is also an object of this invention to provide a new and improved cryosurgical instrument that is inexpensive to construct, splash-proof, leak-proof, insulated, easy to manipulate, and readily filled with refrigerant.

It is a further object of this invention to provide a cryosurgical instrument that is somewhat easier to use, is both splash-proof and leak-proof and has a greater capacity than the cryosurgical instrument described in U.S. Pat. No. 3,536,076.

It is yet another object of this invention to provide an insertion cap that cooperates with a refrigerant canister to aid in the insertion of a refrigerant into an instrument in which the refrigerant is used.

SUMMARY oF THE INVENTION In accordance with principles of this invention, a splash-proof, leak-proof, syringe-type cryosurgical instrument generally formed of merging chambers is provided. The instrument comprises a generally tubular housing that is shaped in a silhouette of a finger-tip at the end of a lower chamber. A thermal conducting probe extends from the interior of the tubular housing to the exterior thereof at the finger-tip shaped end. Preferably, the lower chamberis also surrounded by a thermal insulating layer. An upper chamber of the tubular housing supports a funnel-shaped member for aiding the insertion of a cryogenic fluid (refrigerant) into the housing. The funnel-shaped member is also adapted to prevent the loss of fluid when the housing is inverted or otherwise moved from a generally vertical position. In general, the funnel shaped member includes a plurality of ribs which provide exit passages therebetween. The exit passages allow air and gases to escape when a cryogenic fluid is being introduced into the instrument. In addition, preferably, the funnelshaped member is generally conically shaped at its upper end. The conical portion merges into a generally tubular portion that extends downwardly into the interior of the housing.

In accordance with other principles of this invention, a further apparatus is provided for aiding the insertion of a cryogenic fluid through the funnel-shaped member into the tubular housing. The further apparatus cornprises a cap having a transfer tube projecting outwardly from one end. The cap is adapted to fit onto the 'end of a canister that houses a cryogenic fluid. When the cap is pressed against the cryogenic fluid canister, the cryogenicfluid exits from the canister and flows through the tube. Assuming the tube is inserted through the funnel shaped member and pressing against the ribs of the funnel-shaped member when this action occurs, the fluid passes into the tubular housing. During such insertion, pressure build-up is prevented because exhaust gases are allowed to escape via an escape-port passageway. The escape-port passageway is created by the difference between the outside diameter of the transfer tube and the inside diameter of the tubular portion of the funnel-shaped member and by theapertures between supporting ribs in the upper region of the funnel shaped member.

In accordance with still further principles of this invention, the exterior portion of the probe is surrounded by a portion of the tubular housing and is cut at a predetermined angle, preferably 45. In addition, preferably, a portion of the surrounding tubular housingis undercut so that the rear portion of the probe is exposed while the front portion is covered. Moreover, preferably the upper chamber of the housing has a greater diameter than the lower chamber with the two chambers being joined or merged by a conical chamber.

It will be appreciated, from the foregoing brief summary of the invention, that a relatively uncomplexed and easy to manipulate cryosurgical instrument is provided by the invention. That is, preferably, the lower chamber is generally the size and shape of a comfortably held syringe. The lower chamber conically expands into the upper chamber which rests between the thumb and index finger of a surgeon thereby making the instrument easily manipulable without a loss of feel. In addition, due to the use of merging chambers of different sizes and the use of a funnel-shaped member in the larger upper portion, the instrument can be inverted, either rapidly or slowly, without the loss of the cryogenic fluid. Further, because the forward surface of the metal probe is protected by an extension of the plastic housing and the rear surface is exposed, the instrument can create a larger iceball contact adhesion with the human eye lens tissue while protecting adjacent tissue of the iris when the instrument is used in cataract cryosurgery. Moreover, the inclusion of ribs in the funnel-shaped member not only strengthen the device, but also provide enlarged passageways which form an escape-port system so that gas and air can escape thereby preventing pressure buildup in the instrument during insertion of the cryogenic fluid. Finally, the use of a cap having an outwardly extending transfer tube allows the refrigerant to be deeply inserted into the instrument whereby splashing and sputtering of the refrigerant onto surrounding surfaces during insertion is prevented.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing objects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description when taken in conjunction with the accompanying drawings,

wherein:

FIG. 1 is a prespective view illustrating the overall structure of the cryosurgical instrument of the invention;

FIG. 2 is a cross-sectional view 'of the cryosurgical instrument of the invention along the longitudinal axis thereof;

FIG. 3 is a perspective view illustrating the funnel shaped member;

FIG. 4 is a partial, cross-sectional diagram illustrating a portion of the funnel-shaped member;

FIG. 5 is an exploded perspective view, partially in section, illustrating the actuator-insertion cap portion of the invention;

FIG. 6 is a side view partially in section, illustrating a cryosurgical instrument formed in accordance with the invention held in an inverted position;

FIG. 7 is a cross-sectional diagram of a portion of a human eye;

FIG. 8 is a front view of a human eye having a phantom clock dial superimposed thereover;

FIG. 9 is a cross-sectional view of a human eye wherein the cornea has been raised to allow a cryosurgical instrument to be inserted for the removal of a cataract lens; and,

FIG. 10 is a partial, side view of a thermal conducting probe of the type used in the cryosurgical instrument of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1, 2 and 6 illustrate the overall structure of the invention which comprises a housing 11 having a tubular upper chamber 13; a tubular lowerchamber 15 that has a generally finger shaped (in silhouette) lower tip; and, a conically shaped center chamber 16. The lower chamber 15 is surrounded by a thermally insulating layer 17. Preferably, the housing 11 is unitarily formed of a suitable generally thermally insulating plastic material, such as polypropylene or nylon, for examples.

The finger shaped tip of the lower chamber 15 terminates in a generally downwardly projecting cylindrical region 19. The cylindrical region 19 surrounds a thermally conducting probe 21. The probe 21 is generally cylindrical and includes a fan shaped inner end 23. The inner end 23 of the probe 21 is located inside of the lower chamber 15 of the housing 11.

As best seen in FIGS. 1 and 6, the lower end of the cylindrical region 19 is undercut about an area 25 so that the front cylindrical wall of the probe is covered and the rear cylindrical wall is exposed. As best seen in FIG. 10, the probe 21 is cut at an angle (preferably 45) with respect to its longitudinal axis so as to form a lower, entirely exposed surface that is generally parabolic in shape.

Located inside of the tubular upper chamber 13 of the housing 11 is a funnel-shaped member 27. As illustrated in FIG. 3 the funnel-shaped member 27 comprises a lower tube 30 with sides that are generally parallel to the longitudinal axis of the upper chamber 13. The lower tube 30 is joined in a unitary manner to a generally cylindrical upper region 31 by a conical region 29. The outer diameter of the cylindrical upper re gion 31 of the funnel shaped member 27 is the same as the inner diameter of the cylindrical upper chamber 13 of the housing 11. Hence, when the funnel-shaped member is inserted into the housing 11 in the manner illustrated in FIGS. 2 and 6, it is tightly held therein. To aid in maintaining the funnel-shaped member 27 in the housing 11, a circumferential outwardly extending rib 33 is formed in the outer surface of the generally cylindrical upper region 31 of the funnel-shaped member 27. The upper surface of the rib 33 forms aright angle with respect to the outer surface of the cylindrical upper region 31 and the lower surface forms an acute angle therewith. The rib 33 fits into a suitable, correspondingly shaped, aperture 35 formed in the tubular upper chamber 13 of the housing 11. In addition, the upper area of the cylindrical upper region 31 of the funnel-shaped member 27 includes an outwardly projecting lip 37 which rests on the upper surface of the tubular upper chamber 13. This structural arrangement aides the insertion of the funnel-shaped member while preventing removal thereof.

The funnel-shaped member 27 also includes a plurality of inner ribs 39 which to some extent strengthen the instrument and, as hereinafter described, provide an area against which a cap can be pressed yet allow passageways for gas to exhaust. The lower end of the lower tube 30 of the funnel-shaped member 27 terminates at about the point where the tubular upper chamber region 13 joins the conically shaped center chamber 16.

It will be appreciated from the foregoing description that the invention provides an uncomplicated cryosurgical instrument that includes a funnel-shaped member at its upper end and a thermally insulated lower end. The lower end is a smaller, pen light size section which makes the'instrument easier to handle. The lower end includes a thermally conducting probe adapted to conduct heat from the tip of the probe to a cryogenic fluid located in the housing whereby the probe is cooled. The probe is centrally offset as illustrated in the drawings. The offset arrangement also aids ease of use of the instrument.

While a funnel-shaped member considerably aids the insertion of the cryogenic fluid and prevents the leaking thereof, as suggested by US. Pat. No. 3,536,076, it

has been found that a simple fish-trap structure of the type described in that patent does not entirely solve insertion and leakage problems; For example, a simple funnel-shaped or fish-trap structure allows some splashing of the cryogenic fluid during insertion unless the cryogenic container and the cryosurgical instrument are held in specific positions, such that the fluid is inserted directly downwardly through the funnelshaped structure into the housing. If the positions are not maintained, a small amount of spitting and splashing of the cryogenic fluid may occur. In addition, it has been found that a structure of the type suggested in the foregoing U.S. Pat. can have a slight leakage through the funnel-shaped structure if the instrument is rapidly inverted. While this is not a common occurance, it can happen on some occassions. This invention is adaptedto overcome these problems. The. problem of leakage during inversion is mainly overcomed by the unique use of a conically shaped center chamber 16 that joins the tubular lower chamber to the tubular chamber 13. The intersection thus formed allows the cryogenic liquid to freely flow into the area around the funnel member 27 until it lies in the region 40; illustrated in FIG. 6.

The problem of splashing and spitting during insertion of the cryogenic fluid is mainly solved by the struc- -ture illustrated in FIG. 5. The structure illustrated in FIG. 5 comprises an actuator-insertion cap 4] having a pair of outwardly extending wings 43. The insertion cap is generally cone shaped at one end 44 and generally cylindrical throughout the reinainder of the structure. A cylindrical opening 45 opposite the cone shaped end 44 is adapted to fit over the end 46 of a canister 47 that contains a suitable refrigerant, such as dichlorodifluoromethane with two hundred parts per million ethylene oxide, for example. The end 46 of the canister 47 includes a puncture 'or valve region 49 which is aligned with an inner cylindrical member 51 projecting inwardly. from the cone shaped end 44 of the cap 41. The cylindrical member 51. presses against the puncture region 49 when the fingers and the palm or thumb are used to press the canister against the insertion cap (the fingers lie on the wings 43 and the palm or thumb lie on the rear of the canister) to allow the cryogenic fluid to escape from the canister 47. While as described in U.S. Pat. No. 3,536,076, this structure could be utilized directly to insert the cryogenic fluid through the funnel-shaped member 27 into the housing 11, spitting and splashing of the fluid could occur. The invention improves this basic structure to prevent such spitting and splashing. More specifically, a tube 53 projects outwardly from the center of the cone shaped end 44 of the cap 41. Thetube 53 is long enough to extend entirely through the funnel-shaped member 27 into the housing 11. While the diameter of the tube is relatively small, it is large enough to allow the cryogenic fluid to flow from the canister ,47 into the housing 11. Thus, fluid is directly inserted into the housing 11 whereby spitting and splashing during insertion is entirely prevented.

During insertion, preferably,.the outer flat tip of the cone shaped end 44 surrounding the tube 53 presses against the upper surface ribs 39 of the funnel-shaped member 27. It will be appreciated that this pressing does not entirely close the upper end' of the funnelshaped member 27 because of the nature of the ribs. More specifically, the ribs 39 are formed such that I ing the structure from collapsing under normal pres- In a preferred embodiment of the invention, the wall thickness of the tube 53 is about one thirty-second of an inch and the passageway inside of the tube is also about one thirty-second of an inch in diameter. In addition, the outer surface of the tube 53 is separated from the inner surface of the lower tube 30 of the funnelshaped member 27 by about one thirty-second of an inch. Moreover, preferably, the wall thickness of the funnel-shaped member is one thirty-second of an inch. Hence, the wall thicknesses of the overall structure are relatively thin as are the separation distances. Yet, these distances are sufficientto allow fluid flow into the instrument and gases to escape therefrom in the manner previously described. Further, though the wall of the funnel-shaped member 27 is relatively thin, the strengthening ribs 39 add rigidity that aids in preventsure.

It should be noted that, as illustrated in the drawings, the funnel-shaped member 27 tapers rapidly inwardly to a tube shape that is parallel to the inner wall of the upper chamber 13. This structure is opposedto the angled straight sided funnelshaped structure described in U.S. Pat. No. 3,536,076. It will be appreciated that because of this novel arrangement a greater volume exists between the outer surface of the funnel-shaped member 27 and the inner surface of the tubular upper chamber 13 of the housing 11 than exists in this region of the U.S. Pat. No. 3,536,076 device. The increase in volume in this region allows the present instrument to hold a greater amount of cryogenic fluid than the U.S. Pat. No. 3,536,076 device because this region determines the total volume of cryogenic fluid that can be housed v safely, without'spilling or spitting, when the instrument is suddenly inverted.

Another notable feature of the invention is illustrated best in FIG. 2. More specifically, because the probe end of the instrument is finger shaped, the cryogenic fluid held in the housing contacts a large portion of the interior surface of the probe 21 whereby the probe tip is better cooled. That is, because of the finger shape and location of the probe, a deep region or well 55 is fonned around the probe. This'configuratlon compels the cryogenic fluid orliquid gas-to flow toward the probe 21 at all times. This deep region or well allows extended contact time between the probe and the cryogenic fluid which, in turn, provides for more cryosurgical procedure time than would otherwise be the case if this region were not provided.

It should be noted that, as illustrated in FIG. 2, a portion of the cylindrical periphery .of the probe 21 is, preferably, threaded so that a tight seal is created between the probe 21 and the cylindrical region 19 of the housing 11, i.e., the cylindrical region 19 can be heat shrunk into the threads to forma tight seal therebetween. It should also be noted that the angle the fan shaped region 23 makes with respect to the longitudi nal axis of the overall instrument'is, preferably, the

same as the angle of the probes lower surface with respect to that axis, i.e., 45.

The foregoing description has described a preferred embodiment of the invention, the following is a brief description of the use of the invention in an ophthalmic surgical operation during which a cataract les is removed from the posterior chamber of the human eye by means of the cryosurgical procedure. More specifically, FIG. 7 is a vertical cross-section of a human eye as viewed from the side. The lens 63 of the eye is attached to the ciliary body 65 by zonular fibers 67. Located about the front surface of the lens 63, in the anterior chamber formed between the pupil and the cornea 61, is the iris 69. The cornea is covered by the corneal epithelium 73 which terminates at the bulbar conjunctiva 75.

FIG. 8 is a front view of an eye 74 of the type illustrated in FIG. 7 having a phantom clock dial superimposed thereover. The clock dial is located such that 12 oclock is directly above the eye in the direction of the eyebrow; 3 oclock is on the right side of the eye; 6 oclock is below the eye; and, 9 oclock is on the left side of the eye.

\ During the operation for the removal or delivery of the cataract lens, the doctor normally brings the cryosurgical probe into the eye from the 12 oclock position, i.e., from the top of the head. The probe tip impinges on the cataract lens at either the 3 oclock or the 9 oclock positions because at these positions maximum contact of the strongest portion of the lens tissues and the parabolic face of the probe is made possible. These positions are also used because the oval shape of the tip conforms best to the stronger tissue area at the outer periphery of the lens where the lens is held firmly by the zonular fibers 67. That is, as previously described, when the cylindrical tip of the probe is cut at a predetermined angles, a parabolic oval is formed. The side of the oval is longer than the top or the bottom of the oval. Thus, when the tip is placed in either the 3 oclock or the 9 oclock position the largest peripheral portion of the probe tip is located adjacent to the zonular fibers. Contrawise, if the probe were used in either the 6 or the 12 oclock position, for example, the smallest peripheral portion of the probe tip would be adjacent to the zonular fibers.

In any event, normally, the cornea and corneal epithelium are cut by the use of a suitable instrument (not shown) about the bulbar conjuctiva prior tothe insertion of the probe. A suitable instrument (not shown) is used to raise the cornea and corneal epithelium as illustrated in FIG. 9 so that the anterior chamber is exposed. (The iris is retracted with the repeated instillation of a suitable solution in the conjunctiva] sac of the eye prior to surgery.) Thereafter, the tip of a cryosurgical instrument is laid against the surface of the cataract lens at either the 3 oclock or the 9 oclock positions. With the probe tip in contact with the lens, the lens tissue forms an iceball about the probe face and thereby creates a strong bond or adhesion between the cataract lens and the probe tip. Thereafter, the probe tip is tugged east, west, north and south to separate the lens from the zonular fibers in such a manner as to permit delivery of the cataract lens by cryoextraction. It should be noted that because the rear region (region 25) of the probe of this invention is exposed, as hereinbefore described, larger iceballs causingbetter adherence are formed than would be formed if the probe were not exposed in this region. However, because the forward three quarters front portion of the tip of the probe remains protected, adherence in this area to other portions of the eye is prevented.

It will be appreciated from the foregoing description that the invention provides a new and improved splashproof, leakproof syringe-type cryosurgical instrument. That is, preferably the instrument is in the size of an easily manipulable hand held pen length syringe. Hence, it is easily used by an ophthalmic surgical physician to perform precise cryosurgical or other types of medical operations employing a cryoextractor.

While the invention overcomes the disadvantages of prior art devices of the type described in U.S. Pat. No. 3,536,076, it also improves on the device described in that patent. More specifically, the inventive instrument can house a greater volume of refrigerant because it includes a funnel-shaped member that provides a greater volume between the funnel-shaped member and the walls of the housing. Moreover, the device prevents spitting and splashing during insertion of the cryogenic fluid by the use of a novel cap structure in combination with a canister that houses the cryogenic refrigerant. Further, the inclusion of ribs in the funnel-shaped member allows gases to escape whereby internal pressure buildup in the instrument is prevented. Finally, by combining a longer upper chamber region and a smaller lower chamber region with a sloping conical mid-section, the novel pen-shaped syringe housing may be rapidly inverted without loss of the cryogenic fluid contained in the instrument.

It will be appreciated by those skilled in the art and others that while a preferred embodiment of the invention has been illustrated and described, various changes can be made therein without departing from the spirit and scope of the invention. For example, while four ribs have been illustrated in the drawings, a greater or lesser number can be used, if desired. In addition, while certain dimensions have been described in the specification, various changes can be made therein, as desired. Hence, the invention can be practiced otherwise than as specifically described herein.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as fol lows:

1. In 'a splash-proof, leak-proof, syringe-type cryosurgical instrument comprising:

a. longitudinal housing, suitable for holding a cryogeni'c fluid, said housing having a lower chamber and an upper chamber, said lower chamber having a tip that is finger shaped in silhouette;

a thermal conducting probe mounted in the finger shaped tip of the lower chamber of said housing so as to extend from the interior of said housing to the exterior thereof, said thermal conducting probe adapted to contact a cryogenic fluid held in said housing in a manner such that the tip of said probe is cooled by said cryogenic fluid; and,

funnel-shaped member mounted in the upper chamber of said housing, said funnel-shaped member having a large end defining a large opening located adjacent the top of the upper chamber of said housing and a small end defining a small opening located in said housing for aiding the insertion of said cryogenic fluid from an inserting device, said large end closing the upper chamber so as to prevent said cryogenic fluid from leaving said housing after said fluid has been inserted into said housing;

the improvement wherein said funnel-shaped member includes rib means formed on said funnelshaped member adjacent said large opening for providing an escape port passageway suitable for allowing gas to exhaust to atmosphere during the insertion of a cryogenic fluid into said housing by preventing said inserting device from closing said large opening.

2. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 1 wherein said funnel-shaped member comprises an upper region, an elongated tubular lower region that is smaller in diameter than said upper region, and a tapered region that joins said upper and lower regions.

3. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 2 wherein said rib means of said funnel-shaped member includes a plurality of elongated supporting ribs formed parallel to the longitudinal axis of said funnel-shaped member.

4. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim I wherein said upper and lower chambers are cylindrical in shape, said lower chamber having a smaller diameter than said upper chamber; and including a conically shaped center region that joins said upper andlower chambers.

5. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim .4 wherein said lower chamber of said housing is covered with a thermal insulating material and wherein a well is formed at the end of the lower chamber of said longitudinal housing about the inner end of said thermalconducting probe.

6. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 5 wherein the lower end of said lower chamber extends outwardly and surrounds said probe leaving only the tip of said probe exposed.

7. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 6 wherein the rear portion of the portion of said lower chamber surrounding said probe is undercut so that the rear portion of. said probe is also exposed.

8. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 7 wherein said funnel-shaped member comprises an upper region, an elongated tubular lower region that is smaller in diameter than said upper region, and a tapered region that joins said upper and lower regions. 9. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 8 wherein said rib means of said funnel-shaped member includes a plurality of elongated supporting ribs formed parallel to the longitudinal axis of said funnel-shaped member.

10. A splash-proof, leak-proof, syringe-type cryosur-- gical instrument as claimed in claim 4 wherein said funnel-shaped member comprises an upper region, .an elongated tubular lower region that is smaller in diameter than said upper region, and a tapered region that joins said upper and lower regions.

11. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 10 wherein said rib means of said funnel-shaped member includes a plurality of elongated supporting ribs formed parallel to the longitudinal axis of said funnel-shaped member.

12. In a cryosurgical instrument having an internal chamber suitable for supporting a cryogenic fluid in contact with a probe that extends outwardly from one end of said chamber along the longitudinal axis thereof and an opening at the other end of said chamber adapted to provide for insertion of a cryogenic fluid from an inserting device into said chamber, the improvement comprising a fin means mounted inside said chamber adjacent said opening, said fin means including a plurality of elongated fins attached to said fin means along longitudinal edges at spaced intervals about the periphery of said chamber so as to radiate inwardly in planes located substantially parallel to the longitudinal axis of said chamber adjacent the opening of said cryosurgical instrument, the space between said fins adapted to provide passageways for the escape of air and other gases when a cryosurgical fluid is inserted into said chamber by preventing .said inserting device from closing said opening to said escaping air and other gases. 

1. In a splash-proof, leak-proof, syringe-type cryosurgical instrument comprising: a longitudinal housing suitable for holding a cryogenic fluid, said housing having a lower chamber and an upper chamber, said lower chamber having a tip that is finger shaped in silhouette; a thermal conducting probe mounted in the finger shaped tip of the lower chamber of said housing so as to extend from the interior of said housing to the exterior thereof, said thermal conducting probe adapted to contact a cryogenic fluid held in said housing in a manner such that the tip of said probe is cooled by said cryogenic fluid; and, a funnel-shaped member mounted in the upper chamber of said housing, said funnel-shaped member having a large end defining a large opening located adjacent the top of the upper chamber of said housing and a small end defining a small opening located in said housing for aiding the insertion of said cryogenic fluid from an inserting device, said large end closing the upper chamber so as to prevent said cryogenic fluid from leaving said housing after said fluid has been inserted into said housing; the improvement wherein said funnel-shaped member includes rib means formed on said funnel-shaped member adjacent said large opening for providing an escape port passageway suitable for allowing gas to exhaust to atmosphere during the insertion of a cryogenic fluid into said housing by preventing said inserting device from closing said large opening.
 2. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 1 wherein said funnel-shaped member comprises an upper region, an elongated tubular lower region that is smaller in diameter than said upper region, and a tapered region that joins said upper and lower regions.
 3. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 2 wherein said rib means of said funnel-shaped member includes a plurality of elongated supporting ribs formed parallel to the longitudinal axis of said funnel-shaped member.
 4. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 1 wherein said upper and lower chambers are cylindrical in shape, said lower chamber having a smaller diameter than said upper chamber; and including a conically shaped center region that joins said upper and lower chambers.
 5. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 4 wherein said lower chamber of said housing is covered with a thermal insulating material and wherein a well is formed at the end of the lower chamber of said longitudinal housing about the inner end of said thermal conducting probe.
 6. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 5 wherein the lower end of said lower chamber extends outwardly and surrounds said probe leaving only the tip of said probe exposed.
 7. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 6 wherein the rear portion of the portion of said lower chamber surrounding said probe is undercut so that the rear portion of said probe is also exposed.
 8. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 7 wherein said funnel-shaped member comprises an upper region, an elongated tubular lower region That is smaller in diameter than said upper region, and a tapered region that joins said upper and lower regions.
 9. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 8 wherein said rib means of said funnel-shaped member includes a plurality of elongated supporting ribs formed parallel to the longitudinal axis of said funnel-shaped member.
 10. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 4 wherein said funnel-shaped member comprises an upper region, an elongated tubular lower region that is smaller in diameter than said upper region, and a tapered region that joins said upper and lower regions.
 11. A splash-proof, leak-proof, syringe-type cryosurgical instrument as claimed in claim 10 wherein said rib means of said funnel-shaped member includes a plurality of elongated supporting ribs formed parallel to the longitudinal axis of said funnel-shaped member.
 12. In a cryosurgical instrument having an internal chamber suitable for supporting a cryogenic fluid in contact with a probe that extends outwardly from one end of said chamber along the longitudinal axis thereof and an opening at the other end of said chamber adapted to provide for insertion of a cryogenic fluid from an inserting device into said chamber, the improvement comprising a fin means mounted inside said chamber adjacent said opening, said fin means including a plurality of elongated fins attached to said fin means along longitudinal edges at spaced intervals about the periphery of said chamber so as to radiate inwardly in planes located substantially parallel to the longitudinal axis of said chamber adjacent the opening of said cryosurgical instrument, the space between said fins adapted to provide passageways for the escape of air and other gases when a cryosurgical fluid is inserted into said chamber by preventing said inserting device from closing said opening to said escaping air and other gases. 